Initial import

1 files changed, 2699 insertions, 0 deletions

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
new file mode 100644
index 000000000..9d7b7db75
--- /dev/null
+++ b/drivers/scsi/sg.c
@@ -0,0 +1,2699 @@
+/*
+ *  History:
+ *  Started: Aug 9 by Lawrence Foard (entropy@world.std.com),
+ *           to allow user process control of SCSI devices.
+ *  Development Sponsored by Killy Corp. NY NY
+ *
+ * Original driver (sg.c):
+ *        Copyright (C) 1992 Lawrence Foard
+ * Version 2 and 3 extensions to driver:
+ *        Copyright (C) 1998 - 2014 Douglas Gilbert
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ */
+
+static int sg_version_num = 30536;	/* 2 digits for each component */
+#define SG_VERSION_STR "3.5.36"
+
+/*
+ *  D. P. Gilbert (dgilbert@interlog.com), notes:
+ *      - scsi logging is available via SCSI_LOG_TIMEOUT macros. First
+ *        the kernel/module needs to be built with CONFIG_SCSI_LOGGING
+ *        (otherwise the macros compile to empty statements).
+ *
+ */
+#include <linux/module.h>
+
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/errno.h>
+#include <linux/mtio.h>
+#include <linux/ioctl.h>
+#include <linux/slab.h>
+#include <linux/fcntl.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/moduleparam.h>
+#include <linux/cdev.h>
+#include <linux/idr.h>
+#include <linux/seq_file.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/blktrace_api.h>
+#include <linux/mutex.h>
+#include <linux/atomic.h>
+#include <linux/ratelimit.h>
+#include <linux/uio.h>
+
+#include "scsi.h"
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/sg.h>
+
+#include "scsi_logging.h"
+
+#ifdef CONFIG_SCSI_PROC_FS
+#include <linux/proc_fs.h>
+static char *sg_version_date = "20140603";
+
+static int sg_proc_init(void);
+static void sg_proc_cleanup(void);
+#endif
+
+#define SG_ALLOW_DIO_DEF 0
+
+#define SG_MAX_DEVS 32768
+
+/* SG_MAX_CDB_SIZE should be 260 (spc4r37 section 3.1.30) however the type
+ * of sg_io_hdr::cmd_len can only represent 255. All SCSI commands greater
+ * than 16 bytes are "variable length" whose length is a multiple of 4
+ */
+#define SG_MAX_CDB_SIZE 252
+
+/*
+ * Suppose you want to calculate the formula muldiv(x,m,d)=int(x * m / d)
+ * Then when using 32 bit integers x * m may overflow during the calculation.
+ * Replacing muldiv(x) by muldiv(x)=((x % d) * m) / d + int(x / d) * m
+ * calculates the same, but prevents the overflow when both m and d
+ * are "small" numbers (like HZ and USER_HZ).
+ * Of course an overflow is inavoidable if the result of muldiv doesn't fit
+ * in 32 bits.
+ */
+#define MULDIV(X,MUL,DIV) ((((X % DIV) * MUL) / DIV) + ((X / DIV) * MUL))
+
+#define SG_DEFAULT_TIMEOUT MULDIV(SG_DEFAULT_TIMEOUT_USER, HZ, USER_HZ)
+
+int sg_big_buff = SG_DEF_RESERVED_SIZE;
+/* N.B. This variable is readable and writeable via
+   /proc/scsi/sg/def_reserved_size . Each time sg_open() is called a buffer
+   of this size (or less if there is not enough memory) will be reserved
+   for use by this file descriptor. [Deprecated usage: this variable is also
+   readable via /proc/sys/kernel/sg-big-buff if the sg driver is built into
+   the kernel (i.e. it is not a module).] */
+static int def_reserved_size = -1;	/* picks up init parameter */
+static int sg_allow_dio = SG_ALLOW_DIO_DEF;
+
+static int scatter_elem_sz = SG_SCATTER_SZ;
+static int scatter_elem_sz_prev = SG_SCATTER_SZ;
+
+#define SG_SECTOR_SZ 512
+
+static int sg_add_device(struct device *, struct class_interface *);
+static void sg_remove_device(struct device *, struct class_interface *);
+
+static DEFINE_IDR(sg_index_idr);
+static DEFINE_RWLOCK(sg_index_lock);	/* Also used to lock
+							   file descriptor list for device */
+
+static struct class_interface sg_interface = {
+	.add_dev        = sg_add_device,
+	.remove_dev     = sg_remove_device,
+};
+
+typedef struct sg_scatter_hold { /* holding area for scsi scatter gather info */
+	unsigned short k_use_sg; /* Count of kernel scatter-gather pieces */
+	unsigned sglist_len; /* size of malloc'd scatter-gather list ++ */
+	unsigned bufflen;	/* Size of (aggregate) data buffer */
+	struct page **pages;
+	int page_order;
+	char dio_in_use;	/* 0->indirect IO (or mmap), 1->dio */
+	unsigned char cmd_opcode; /* first byte of command */
+} Sg_scatter_hold;
+
+struct sg_device;		/* forward declarations */
+struct sg_fd;
+
+typedef struct sg_request {	/* SG_MAX_QUEUE requests outstanding per file */
+	struct sg_request *nextrp;	/* NULL -> tail request (slist) */
+	struct sg_fd *parentfp;	/* NULL -> not in use */
+	Sg_scatter_hold data;	/* hold buffer, perhaps scatter list */
+	sg_io_hdr_t header;	/* scsi command+info, see <scsi/sg.h> */
+	unsigned char sense_b[SCSI_SENSE_BUFFERSIZE];
+	char res_used;		/* 1 -> using reserve buffer, 0 -> not ... */
+	char orphan;		/* 1 -> drop on sight, 0 -> normal */
+	char sg_io_owned;	/* 1 -> packet belongs to SG_IO */
+	/* done protected by rq_list_lock */
+	char done;		/* 0->before bh, 1->before read, 2->read */
+	struct request *rq;
+	struct bio *bio;
+	struct execute_work ew;
+} Sg_request;
+
+typedef struct sg_fd {		/* holds the state of a file descriptor */
+	struct list_head sfd_siblings;  /* protected by device's sfd_lock */
+	struct sg_device *parentdp;	/* owning device */
+	wait_queue_head_t read_wait;	/* queue read until command done */
+	rwlock_t rq_list_lock;	/* protect access to list in req_arr */
+	int timeout;		/* defaults to SG_DEFAULT_TIMEOUT      */
+	int timeout_user;	/* defaults to SG_DEFAULT_TIMEOUT_USER */
+	Sg_scatter_hold reserve;	/* buffer held for this file descriptor */
+	unsigned save_scat_len;	/* original length of trunc. scat. element */
+	Sg_request *headrp;	/* head of request slist, NULL->empty */
+	struct fasync_struct *async_qp;	/* used by asynchronous notification */
+	Sg_request req_arr[SG_MAX_QUEUE];	/* used as singly-linked list */
+	char low_dma;		/* as in parent but possibly overridden to 1 */
+	char force_packid;	/* 1 -> pack_id input to read(), 0 -> ignored */
+	char cmd_q;		/* 1 -> allow command queuing, 0 -> don't */
+	unsigned char next_cmd_len; /* 0: automatic, >0: use on next write() */
+	char keep_orphan;	/* 0 -> drop orphan (def), 1 -> keep for read() */
+	char mmap_called;	/* 0 -> mmap() never called on this fd */
+	struct kref f_ref;
+	struct execute_work ew;
+} Sg_fd;
+
+typedef struct sg_device { /* holds the state of each scsi generic device */
+	struct scsi_device *device;
+	wait_queue_head_t open_wait;    /* queue open() when O_EXCL present */
+	struct mutex open_rel_lock;     /* held when in open() or release() */
+	int sg_tablesize;	/* adapter's max scatter-gather table size */
+	u32 index;		/* device index number */
+	struct list_head sfds;
+	rwlock_t sfd_lock;      /* protect access to sfd list */
+	atomic_t detaching;     /* 0->device usable, 1->device detaching */
+	bool exclude;		/* 1->open(O_EXCL) succeeded and is active */
+	int open_cnt;		/* count of opens (perhaps < num(sfds) ) */
+	char sgdebug;		/* 0->off, 1->sense, 9->dump dev, 10-> all devs */
+	struct gendisk *disk;
+	struct cdev * cdev;	/* char_dev [sysfs: /sys/cdev/major/sg<n>] */
+	struct kref d_ref;
+} Sg_device;
+
+/* tasklet or soft irq callback */
+static void sg_rq_end_io(struct request *rq, int uptodate);
+static int sg_start_req(Sg_request *srp, unsigned char *cmd);
+static int sg_finish_rem_req(Sg_request * srp);
+static int sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size);
+static ssize_t sg_new_read(Sg_fd * sfp, char __user *buf, size_t count,
+			   Sg_request * srp);
+static ssize_t sg_new_write(Sg_fd *sfp, struct file *file,
+			const char __user *buf, size_t count, int blocking,
+			int read_only, int sg_io_owned, Sg_request **o_srp);
+static int sg_common_write(Sg_fd * sfp, Sg_request * srp,
+			   unsigned char *cmnd, int timeout, int blocking);
+static int sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer);
+static void sg_remove_scat(Sg_fd * sfp, Sg_scatter_hold * schp);
+static void sg_build_reserve(Sg_fd * sfp, int req_size);
+static void sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size);
+static void sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp);
+static Sg_fd *sg_add_sfp(Sg_device * sdp);
+static void sg_remove_sfp(struct kref *);
+static Sg_request *sg_get_rq_mark(Sg_fd * sfp, int pack_id);
+static Sg_request *sg_add_request(Sg_fd * sfp);
+static int sg_remove_request(Sg_fd * sfp, Sg_request * srp);
+static int sg_res_in_use(Sg_fd * sfp);
+static Sg_device *sg_get_dev(int dev);
+static void sg_device_destroy(struct kref *kref);
+
+#define SZ_SG_HEADER sizeof(struct sg_header)
+#define SZ_SG_IO_HDR sizeof(sg_io_hdr_t)
+#define SZ_SG_IOVEC sizeof(sg_iovec_t)
+#define SZ_SG_REQ_INFO sizeof(sg_req_info_t)
+
+#define sg_printk(prefix, sdp, fmt, a...) \
+	sdev_prefix_printk(prefix, (sdp)->device,		\
+			   (sdp)->disk->disk_name, fmt, ##a)
+
+static int sg_allow_access(struct file *filp, unsigned char *cmd)
+{
+	struct sg_fd *sfp = filp->private_data;
+
+	if (sfp->parentdp->device->type == TYPE_SCANNER)
+		return 0;
+
+	return blk_verify_command(cmd, filp->f_mode & FMODE_WRITE);
+}
+
+static int
+open_wait(Sg_device *sdp, int flags)
+{
+	int retval = 0;
+
+	if (flags & O_EXCL) {
+		while (sdp->open_cnt > 0) {
+			mutex_unlock(&sdp->open_rel_lock);
+			retval = wait_event_interruptible(sdp->open_wait,
+					(atomic_read(&sdp->detaching) ||
+					 !sdp->open_cnt));
+			mutex_lock(&sdp->open_rel_lock);
+
+			if (retval) /* -ERESTARTSYS */
+				return retval;
+			if (atomic_read(&sdp->detaching))
+				return -ENODEV;
+		}
+	} else {
+		while (sdp->exclude) {
+			mutex_unlock(&sdp->open_rel_lock);
+			retval = wait_event_interruptible(sdp->open_wait,
+					(atomic_read(&sdp->detaching) ||
+					 !sdp->exclude));
+			mutex_lock(&sdp->open_rel_lock);
+
+			if (retval) /* -ERESTARTSYS */
+				return retval;
+			if (atomic_read(&sdp->detaching))
+				return -ENODEV;
+		}
+	}
+
+	return retval;
+}
+
+/* Returns 0 on success, else a negated errno value */
+static int
+sg_open(struct inode *inode, struct file *filp)
+{
+	int dev = iminor(inode);
+	int flags = filp->f_flags;
+	struct request_queue *q;
+	Sg_device *sdp;
+	Sg_fd *sfp;
+	int retval;
+
+	nonseekable_open(inode, filp);
+	if ((flags & O_EXCL) && (O_RDONLY == (flags & O_ACCMODE)))
+		return -EPERM; /* Can't lock it with read only access */
+	sdp = sg_get_dev(dev);
+	if (IS_ERR(sdp))
+		return PTR_ERR(sdp);
+
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				      "sg_open: flags=0x%x\n", flags));
+
+	/* This driver's module count bumped by fops_get in <linux/fs.h> */
+	/* Prevent the device driver from vanishing while we sleep */
+	retval = scsi_device_get(sdp->device);
+	if (retval)
+		goto sg_put;
+
+	retval = scsi_autopm_get_device(sdp->device);
+	if (retval)
+		goto sdp_put;
+
+	/* scsi_block_when_processing_errors() may block so bypass
+	 * check if O_NONBLOCK. Permits SCSI commands to be issued
+	 * during error recovery. Tread carefully. */
+	if (!((flags & O_NONBLOCK) ||
+	      scsi_block_when_processing_errors(sdp->device))) {
+		retval = -ENXIO;
+		/* we are in error recovery for this device */
+		goto error_out;
+	}
+
+	mutex_lock(&sdp->open_rel_lock);
+	if (flags & O_NONBLOCK) {
+		if (flags & O_EXCL) {
+			if (sdp->open_cnt > 0) {
+				retval = -EBUSY;
+				goto error_mutex_locked;
+			}
+		} else {
+			if (sdp->exclude) {
+				retval = -EBUSY;
+				goto error_mutex_locked;
+			}
+		}
+	} else {
+		retval = open_wait(sdp, flags);
+		if (retval) /* -ERESTARTSYS or -ENODEV */
+			goto error_mutex_locked;
+	}
+
+	/* N.B. at this point we are holding the open_rel_lock */
+	if (flags & O_EXCL)
+		sdp->exclude = true;
+
+	if (sdp->open_cnt < 1) {  /* no existing opens */
+		sdp->sgdebug = 0;
+		q = sdp->device->request_queue;
+		sdp->sg_tablesize = queue_max_segments(q);
+	}
+	sfp = sg_add_sfp(sdp);
+	if (IS_ERR(sfp)) {
+		retval = PTR_ERR(sfp);
+		goto out_undo;
+	}
+
+	filp->private_data = sfp;
+	sdp->open_cnt++;
+	mutex_unlock(&sdp->open_rel_lock);
+
+	retval = 0;
+sg_put:
+	kref_put(&sdp->d_ref, sg_device_destroy);
+	return retval;
+
+out_undo:
+	if (flags & O_EXCL) {
+		sdp->exclude = false;   /* undo if error */
+		wake_up_interruptible(&sdp->open_wait);
+	}
+error_mutex_locked:
+	mutex_unlock(&sdp->open_rel_lock);
+error_out:
+	scsi_autopm_put_device(sdp->device);
+sdp_put:
+	scsi_device_put(sdp->device);
+	goto sg_put;
+}
+
+/* Release resources associated with a successful sg_open()
+ * Returns 0 on success, else a negated errno value */
+static int
+sg_release(struct inode *inode, struct file *filp)
+{
+	Sg_device *sdp;
+	Sg_fd *sfp;
+
+	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
+		return -ENXIO;
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp, "sg_release\n"));
+
+	mutex_lock(&sdp->open_rel_lock);
+	scsi_autopm_put_device(sdp->device);
+	kref_put(&sfp->f_ref, sg_remove_sfp);
+	sdp->open_cnt--;
+
+	/* possibly many open()s waiting on exlude clearing, start many;
+	 * only open(O_EXCL)s wait on 0==open_cnt so only start one */
+	if (sdp->exclude) {
+		sdp->exclude = false;
+		wake_up_interruptible_all(&sdp->open_wait);
+	} else if (0 == sdp->open_cnt) {
+		wake_up_interruptible(&sdp->open_wait);
+	}
+	mutex_unlock(&sdp->open_rel_lock);
+	return 0;
+}
+
+static ssize_t
+sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
+{
+	Sg_device *sdp;
+	Sg_fd *sfp;
+	Sg_request *srp;
+	int req_pack_id = -1;
+	sg_io_hdr_t *hp;
+	struct sg_header *old_hdr = NULL;
+	int retval = 0;
+
+	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
+		return -ENXIO;
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				      "sg_read: count=%d\n", (int) count));
+
+	if (!access_ok(VERIFY_WRITE, buf, count))
+		return -EFAULT;
+	if (sfp->force_packid && (count >= SZ_SG_HEADER)) {
+		old_hdr = kmalloc(SZ_SG_HEADER, GFP_KERNEL);
+		if (!old_hdr)
+			return -ENOMEM;
+		if (__copy_from_user(old_hdr, buf, SZ_SG_HEADER)) {
+			retval = -EFAULT;
+			goto free_old_hdr;
+		}
+		if (old_hdr->reply_len < 0) {
+			if (count >= SZ_SG_IO_HDR) {
+				sg_io_hdr_t *new_hdr;
+				new_hdr = kmalloc(SZ_SG_IO_HDR, GFP_KERNEL);
+				if (!new_hdr) {
+					retval = -ENOMEM;
+					goto free_old_hdr;
+				}
+				retval =__copy_from_user
+				    (new_hdr, buf, SZ_SG_IO_HDR);
+				req_pack_id = new_hdr->pack_id;
+				kfree(new_hdr);
+				if (retval) {
+					retval = -EFAULT;
+					goto free_old_hdr;
+				}
+			}
+		} else
+			req_pack_id = old_hdr->pack_id;
+	}
+	srp = sg_get_rq_mark(sfp, req_pack_id);
+	if (!srp) {		/* now wait on packet to arrive */
+		if (atomic_read(&sdp->detaching)) {
+			retval = -ENODEV;
+			goto free_old_hdr;
+		}
+		if (filp->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto free_old_hdr;
+		}
+		retval = wait_event_interruptible(sfp->read_wait,
+			(atomic_read(&sdp->detaching) ||
+			(srp = sg_get_rq_mark(sfp, req_pack_id))));
+		if (atomic_read(&sdp->detaching)) {
+			retval = -ENODEV;
+			goto free_old_hdr;
+		}
+		if (retval) {
+			/* -ERESTARTSYS as signal hit process */
+			goto free_old_hdr;
+		}
+	}
+	if (srp->header.interface_id != '\0') {
+		retval = sg_new_read(sfp, buf, count, srp);
+		goto free_old_hdr;
+	}
+
+	hp = &srp->header;
+	if (old_hdr == NULL) {
+		old_hdr = kmalloc(SZ_SG_HEADER, GFP_KERNEL);
+		if (! old_hdr) {
+			retval = -ENOMEM;
+			goto free_old_hdr;
+		}
+	}
+	memset(old_hdr, 0, SZ_SG_HEADER);
+	old_hdr->reply_len = (int) hp->timeout;
+	old_hdr->pack_len = old_hdr->reply_len; /* old, strange behaviour */
+	old_hdr->pack_id = hp->pack_id;
+	old_hdr->twelve_byte =
+	    ((srp->data.cmd_opcode >= 0xc0) && (12 == hp->cmd_len)) ? 1 : 0;
+	old_hdr->target_status = hp->masked_status;
+	old_hdr->host_status = hp->host_status;
+	old_hdr->driver_status = hp->driver_status;
+	if ((CHECK_CONDITION & hp->masked_status) ||
+	    (DRIVER_SENSE & hp->driver_status))
+		memcpy(old_hdr->sense_buffer, srp->sense_b,
+		       sizeof (old_hdr->sense_buffer));
+	switch (hp->host_status) {
+	/* This setup of 'result' is for backward compatibility and is best
+	   ignored by the user who should use target, host + driver status */
+	case DID_OK:
+	case DID_PASSTHROUGH:
+	case DID_SOFT_ERROR:
+		old_hdr->result = 0;
+		break;
+	case DID_NO_CONNECT:
+	case DID_BUS_BUSY:
+	case DID_TIME_OUT:
+		old_hdr->result = EBUSY;
+		break;
+	case DID_BAD_TARGET:
+	case DID_ABORT:
+	case DID_PARITY:
+	case DID_RESET:
+	case DID_BAD_INTR:
+		old_hdr->result = EIO;
+		break;
+	case DID_ERROR:
+		old_hdr->result = (srp->sense_b[0] == 0 && 
+				  hp->masked_status == GOOD) ? 0 : EIO;
+		break;
+	default:
+		old_hdr->result = EIO;
+		break;
+	}
+
+	/* Now copy the result back to the user buffer.  */
+	if (count >= SZ_SG_HEADER) {
+		if (__copy_to_user(buf, old_hdr, SZ_SG_HEADER)) {
+			retval = -EFAULT;
+			goto free_old_hdr;
+		}
+		buf += SZ_SG_HEADER;
+		if (count > old_hdr->reply_len)
+			count = old_hdr->reply_len;
+		if (count > SZ_SG_HEADER) {
+			if (sg_read_oxfer(srp, buf, count - SZ_SG_HEADER)) {
+				retval = -EFAULT;
+				goto free_old_hdr;
+			}
+		}
+	} else
+		count = (old_hdr->result == 0) ? 0 : -EIO;
+	sg_finish_rem_req(srp);
+	retval = count;
+free_old_hdr:
+	kfree(old_hdr);
+	return retval;
+}
+
+static ssize_t
+sg_new_read(Sg_fd * sfp, char __user *buf, size_t count, Sg_request * srp)
+{
+	sg_io_hdr_t *hp = &srp->header;
+	int err = 0, err2;
+	int len;
+
+	if (count < SZ_SG_IO_HDR) {
+		err = -EINVAL;
+		goto err_out;
+	}
+	hp->sb_len_wr = 0;
+	if ((hp->mx_sb_len > 0) && hp->sbp) {
+		if ((CHECK_CONDITION & hp->masked_status) ||
+		    (DRIVER_SENSE & hp->driver_status)) {
+			int sb_len = SCSI_SENSE_BUFFERSIZE;
+			sb_len = (hp->mx_sb_len > sb_len) ? sb_len : hp->mx_sb_len;
+			len = 8 + (int) srp->sense_b[7];	/* Additional sense length field */
+			len = (len > sb_len) ? sb_len : len;
+			if (copy_to_user(hp->sbp, srp->sense_b, len)) {
+				err = -EFAULT;
+				goto err_out;
+			}
+			hp->sb_len_wr = len;
+		}
+	}
+	if (hp->masked_status || hp->host_status || hp->driver_status)
+		hp->info |= SG_INFO_CHECK;
+	if (copy_to_user(buf, hp, SZ_SG_IO_HDR)) {
+		err = -EFAULT;
+		goto err_out;
+	}
+err_out:
+	err2 = sg_finish_rem_req(srp);
+	return err ? : err2 ? : count;
+}
+
+static ssize_t
+sg_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
+{
+	int mxsize, cmd_size, k;
+	int input_size, blocking;
+	unsigned char opcode;
+	Sg_device *sdp;
+	Sg_fd *sfp;
+	Sg_request *srp;
+	struct sg_header old_hdr;
+	sg_io_hdr_t *hp;
+	unsigned char cmnd[SG_MAX_CDB_SIZE];
+
+	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
+		return -ENXIO;
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				      "sg_write: count=%d\n", (int) count));
+	if (atomic_read(&sdp->detaching))
+		return -ENODEV;
+	if (!((filp->f_flags & O_NONBLOCK) ||
+	      scsi_block_when_processing_errors(sdp->device)))
+		return -ENXIO;
+
+	if (!access_ok(VERIFY_READ, buf, count))
+		return -EFAULT;	/* protects following copy_from_user()s + get_user()s */
+	if (count < SZ_SG_HEADER)
+		return -EIO;
+	if (__copy_from_user(&old_hdr, buf, SZ_SG_HEADER))
+		return -EFAULT;
+	blocking = !(filp->f_flags & O_NONBLOCK);
+	if (old_hdr.reply_len < 0)
+		return sg_new_write(sfp, filp, buf, count,
+				    blocking, 0, 0, NULL);
+	if (count < (SZ_SG_HEADER + 6))
+		return -EIO;	/* The minimum scsi command length is 6 bytes. */
+
+	if (!(srp = sg_add_request(sfp))) {
+		SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sdp,
+					      "sg_write: queue full\n"));
+		return -EDOM;
+	}
+	buf += SZ_SG_HEADER;
+	__get_user(opcode, buf);
+	if (sfp->next_cmd_len > 0) {
+		cmd_size = sfp->next_cmd_len;
+		sfp->next_cmd_len = 0;	/* reset so only this write() effected */
+	} else {
+		cmd_size = COMMAND_SIZE(opcode);	/* based on SCSI command group */
+		if ((opcode >= 0xc0) && old_hdr.twelve_byte)
+			cmd_size = 12;
+	}
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sdp,
+		"sg_write:   scsi opcode=0x%02x, cmd_size=%d\n", (int) opcode, cmd_size));
+/* Determine buffer size.  */
+	input_size = count - cmd_size;
+	mxsize = (input_size > old_hdr.reply_len) ? input_size : old_hdr.reply_len;
+	mxsize -= SZ_SG_HEADER;
+	input_size -= SZ_SG_HEADER;
+	if (input_size < 0) {
+		sg_remove_request(sfp, srp);
+		return -EIO;	/* User did not pass enough bytes for this command. */
+	}
+	hp = &srp->header;
+	hp->interface_id = '\0';	/* indicator of old interface tunnelled */
+	hp->cmd_len = (unsigned char) cmd_size;
+	hp->iovec_count = 0;
+	hp->mx_sb_len = 0;
+	if (input_size > 0)
+		hp->dxfer_direction = (old_hdr.reply_len > SZ_SG_HEADER) ?
+		    SG_DXFER_TO_FROM_DEV : SG_DXFER_TO_DEV;
+	else
+		hp->dxfer_direction = (mxsize > 0) ? SG_DXFER_FROM_DEV : SG_DXFER_NONE;
+	hp->dxfer_len = mxsize;
+	if (hp->dxfer_direction == SG_DXFER_TO_DEV)
+		hp->dxferp = (char __user *)buf + cmd_size;
+	else
+		hp->dxferp = NULL;
+	hp->sbp = NULL;
+	hp->timeout = old_hdr.reply_len;	/* structure abuse ... */
+	hp->flags = input_size;	/* structure abuse ... */
+	hp->pack_id = old_hdr.pack_id;
+	hp->usr_ptr = NULL;
+	if (__copy_from_user(cmnd, buf, cmd_size))
+		return -EFAULT;
+	/*
+	 * SG_DXFER_TO_FROM_DEV is functionally equivalent to SG_DXFER_FROM_DEV,
+	 * but is is possible that the app intended SG_DXFER_TO_DEV, because there
+	 * is a non-zero input_size, so emit a warning.
+	 */
+	if (hp->dxfer_direction == SG_DXFER_TO_FROM_DEV) {
+		static char cmd[TASK_COMM_LEN];
+		if (strcmp(current->comm, cmd)) {
+			printk_ratelimited(KERN_WARNING
+					   "sg_write: data in/out %d/%d bytes "
+					   "for SCSI command 0x%x-- guessing "
+					   "data in;\n   program %s not setting "
+					   "count and/or reply_len properly\n",
+					   old_hdr.reply_len - (int)SZ_SG_HEADER,
+					   input_size, (unsigned int) cmnd[0],
+					   current->comm);
+			strcpy(cmd, current->comm);
+		}
+	}
+	k = sg_common_write(sfp, srp, cmnd, sfp->timeout, blocking);
+	return (k < 0) ? k : count;
+}
+
+static ssize_t
+sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,
+		 size_t count, int blocking, int read_only, int sg_io_owned,
+		 Sg_request **o_srp)
+{
+	int k;
+	Sg_request *srp;
+	sg_io_hdr_t *hp;
+	unsigned char cmnd[SG_MAX_CDB_SIZE];
+	int timeout;
+	unsigned long ul_timeout;
+
+	if (count < SZ_SG_IO_HDR)
+		return -EINVAL;
+	if (!access_ok(VERIFY_READ, buf, count))
+		return -EFAULT; /* protects following copy_from_user()s + get_user()s */
+
+	sfp->cmd_q = 1;	/* when sg_io_hdr seen, set command queuing on */
+	if (!(srp = sg_add_request(sfp))) {
+		SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
+					      "sg_new_write: queue full\n"));
+		return -EDOM;
+	}
+	srp->sg_io_owned = sg_io_owned;
+	hp = &srp->header;
+	if (__copy_from_user(hp, buf, SZ_SG_IO_HDR)) {
+		sg_remove_request(sfp, srp);
+		return -EFAULT;
+	}
+	if (hp->interface_id != 'S') {
+		sg_remove_request(sfp, srp);
+		return -ENOSYS;
+	}
+	if (hp->flags & SG_FLAG_MMAP_IO) {
+		if (hp->dxfer_len > sfp->reserve.bufflen) {
+			sg_remove_request(sfp, srp);
+			return -ENOMEM;	/* MMAP_IO size must fit in reserve buffer */
+		}
+		if (hp->flags & SG_FLAG_DIRECT_IO) {
+			sg_remove_request(sfp, srp);
+			return -EINVAL;	/* either MMAP_IO or DIRECT_IO (not both) */
+		}
+		if (sg_res_in_use(sfp)) {
+			sg_remove_request(sfp, srp);
+			return -EBUSY;	/* reserve buffer already being used */
+		}
+	}
+	ul_timeout = msecs_to_jiffies(srp->header.timeout);
+	timeout = (ul_timeout < INT_MAX) ? ul_timeout : INT_MAX;
+	if ((!hp->cmdp) || (hp->cmd_len < 6) || (hp->cmd_len > sizeof (cmnd))) {
+		sg_remove_request(sfp, srp);
+		return -EMSGSIZE;
+	}
+	if (!access_ok(VERIFY_READ, hp->cmdp, hp->cmd_len)) {
+		sg_remove_request(sfp, srp);
+		return -EFAULT;	/* protects following copy_from_user()s + get_user()s */
+	}
+	if (__copy_from_user(cmnd, hp->cmdp, hp->cmd_len)) {
+		sg_remove_request(sfp, srp);
+		return -EFAULT;
+	}
+	if (read_only && sg_allow_access(file, cmnd)) {
+		sg_remove_request(sfp, srp);
+		return -EPERM;
+	}
+	k = sg_common_write(sfp, srp, cmnd, timeout, blocking);
+	if (k < 0)
+		return k;
+	if (o_srp)
+		*o_srp = srp;
+	return count;
+}
+
+static int
+sg_common_write(Sg_fd * sfp, Sg_request * srp,
+		unsigned char *cmnd, int timeout, int blocking)
+{
+	int k, at_head;
+	Sg_device *sdp = sfp->parentdp;
+	sg_io_hdr_t *hp = &srp->header;
+
+	srp->data.cmd_opcode = cmnd[0];	/* hold opcode of command */
+	hp->status = 0;
+	hp->masked_status = 0;
+	hp->msg_status = 0;
+	hp->info = 0;
+	hp->host_status = 0;
+	hp->driver_status = 0;
+	hp->resid = 0;
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
+			"sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
+			(int) cmnd[0], (int) hp->cmd_len));
+
+	k = sg_start_req(srp, cmnd);
+	if (k) {
+		SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
+			"sg_common_write: start_req err=%d\n", k));
+		sg_finish_rem_req(srp);
+		return k;	/* probably out of space --> ENOMEM */
+	}
+	if (atomic_read(&sdp->detaching)) {
+		if (srp->bio)
+			blk_end_request_all(srp->rq, -EIO);
+		sg_finish_rem_req(srp);
+		return -ENODEV;
+	}
+
+	hp->duration = jiffies_to_msecs(jiffies);
+	if (hp->interface_id != '\0' &&	/* v3 (or later) interface */
+	    (SG_FLAG_Q_AT_TAIL & hp->flags))
+		at_head = 0;
+	else
+		at_head = 1;
+
+	srp->rq->timeout = timeout;
+	kref_get(&sfp->f_ref); /* sg_rq_end_io() does kref_put(). */
+	blk_execute_rq_nowait(sdp->device->request_queue, sdp->disk,
+			      srp->rq, at_head, sg_rq_end_io);
+	return 0;
+}
+
+static int srp_done(Sg_fd *sfp, Sg_request *srp)
+{
+	unsigned long flags;
+	int ret;
+
+	read_lock_irqsave(&sfp->rq_list_lock, flags);
+	ret = srp->done;
+	read_unlock_irqrestore(&sfp->rq_list_lock, flags);
+	return ret;
+}
+
+static int max_sectors_bytes(struct request_queue *q)
+{
+	unsigned int max_sectors = queue_max_sectors(q);
+
+	max_sectors = min_t(unsigned int, max_sectors, INT_MAX >> 9);
+
+	return max_sectors << 9;
+}
+
+static long
+sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
+{
+	void __user *p = (void __user *)arg;
+	int __user *ip = p;
+	int result, val, read_only;
+	Sg_device *sdp;
+	Sg_fd *sfp;
+	Sg_request *srp;
+	unsigned long iflags;
+
+	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
+		return -ENXIO;
+
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				   "sg_ioctl: cmd=0x%x\n", (int) cmd_in));
+	read_only = (O_RDWR != (filp->f_flags & O_ACCMODE));
+
+	switch (cmd_in) {
+	case SG_IO:
+		if (atomic_read(&sdp->detaching))
+			return -ENODEV;
+		if (!scsi_block_when_processing_errors(sdp->device))
+			return -ENXIO;
+		if (!access_ok(VERIFY_WRITE, p, SZ_SG_IO_HDR))
+			return -EFAULT;
+		result = sg_new_write(sfp, filp, p, SZ_SG_IO_HDR,
+				 1, read_only, 1, &srp);
+		if (result < 0)
+			return result;
+		result = wait_event_interruptible(sfp->read_wait,
+			(srp_done(sfp, srp) || atomic_read(&sdp->detaching)));
+		if (atomic_read(&sdp->detaching))
+			return -ENODEV;
+		write_lock_irq(&sfp->rq_list_lock);
+		if (srp->done) {
+			srp->done = 2;
+			write_unlock_irq(&sfp->rq_list_lock);
+			result = sg_new_read(sfp, p, SZ_SG_IO_HDR, srp);
+			return (result < 0) ? result : 0;
+		}
+		srp->orphan = 1;
+		write_unlock_irq(&sfp->rq_list_lock);
+		return result;	/* -ERESTARTSYS because signal hit process */
+	case SG_SET_TIMEOUT:
+		result = get_user(val, ip);
+		if (result)
+			return result;
+		if (val < 0)
+			return -EIO;
+		if (val >= MULDIV (INT_MAX, USER_HZ, HZ))
+		    val = MULDIV (INT_MAX, USER_HZ, HZ);
+		sfp->timeout_user = val;
+		sfp->timeout = MULDIV (val, HZ, USER_HZ);
+
+		return 0;
+	case SG_GET_TIMEOUT:	/* N.B. User receives timeout as return value */
+				/* strange ..., for backward compatibility */
+		return sfp->timeout_user;
+	case SG_SET_FORCE_LOW_DMA:
+		result = get_user(val, ip);
+		if (result)
+			return result;
+		if (val) {
+			sfp->low_dma = 1;
+			if ((0 == sfp->low_dma) && (0 == sg_res_in_use(sfp))) {
+				val = (int) sfp->reserve.bufflen;
+				sg_remove_scat(sfp, &sfp->reserve);
+				sg_build_reserve(sfp, val);
+			}
+		} else {
+			if (atomic_read(&sdp->detaching))
+				return -ENODEV;
+			sfp->low_dma = sdp->device->host->unchecked_isa_dma;
+		}
+		return 0;
+	case SG_GET_LOW_DMA:
+		return put_user((int) sfp->low_dma, ip);
+	case SG_GET_SCSI_ID:
+		if (!access_ok(VERIFY_WRITE, p, sizeof (sg_scsi_id_t)))
+			return -EFAULT;
+		else {
+			sg_scsi_id_t __user *sg_idp = p;
+
+			if (atomic_read(&sdp->detaching))
+				return -ENODEV;
+			__put_user((int) sdp->device->host->host_no,
+				   &sg_idp->host_no);
+			__put_user((int) sdp->device->channel,
+				   &sg_idp->channel);
+			__put_user((int) sdp->device->id, &sg_idp->scsi_id);
+			__put_user((int) sdp->device->lun, &sg_idp->lun);
+			__put_user((int) sdp->device->type, &sg_idp->scsi_type);
+			__put_user((short) sdp->device->host->cmd_per_lun,
+				   &sg_idp->h_cmd_per_lun);
+			__put_user((short) sdp->device->queue_depth,
+				   &sg_idp->d_queue_depth);
+			__put_user(0, &sg_idp->unused[0]);
+			__put_user(0, &sg_idp->unused[1]);
+			return 0;
+		}
+	case SG_SET_FORCE_PACK_ID:
+		result = get_user(val, ip);
+		if (result)
+			return result;
+		sfp->force_packid = val ? 1 : 0;
+		return 0;
+	case SG_GET_PACK_ID:
+		if (!access_ok(VERIFY_WRITE, ip, sizeof (int)))
+			return -EFAULT;
+		read_lock_irqsave(&sfp->rq_list_lock, iflags);
+		for (srp = sfp->headrp; srp; srp = srp->nextrp) {
+			if ((1 == srp->done) && (!srp->sg_io_owned)) {
+				read_unlock_irqrestore(&sfp->rq_list_lock,
+						       iflags);
+				__put_user(srp->header.pack_id, ip);
+				return 0;
+			}
+		}
+		read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+		__put_user(-1, ip);
+		return 0;
+	case SG_GET_NUM_WAITING:
+		read_lock_irqsave(&sfp->rq_list_lock, iflags);
+		for (val = 0, srp = sfp->headrp; srp; srp = srp->nextrp) {
+			if ((1 == srp->done) && (!srp->sg_io_owned))
+				++val;
+		}
+		read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+		return put_user(val, ip);
+	case SG_GET_SG_TABLESIZE:
+		return put_user(sdp->sg_tablesize, ip);
+	case SG_SET_RESERVED_SIZE:
+		result = get_user(val, ip);
+		if (result)
+			return result;
+                if (val < 0)
+                        return -EINVAL;
+		val = min_t(int, val,
+			    max_sectors_bytes(sdp->device->request_queue));
+		if (val != sfp->reserve.bufflen) {
+			if (sg_res_in_use(sfp) || sfp->mmap_called)
+				return -EBUSY;
+			sg_remove_scat(sfp, &sfp->reserve);
+			sg_build_reserve(sfp, val);
+		}
+		return 0;
+	case SG_GET_RESERVED_SIZE:
+		val = min_t(int, sfp->reserve.bufflen,
+			    max_sectors_bytes(sdp->device->request_queue));
+		return put_user(val, ip);
+	case SG_SET_COMMAND_Q:
+		result = get_user(val, ip);
+		if (result)
+			return result;
+		sfp->cmd_q = val ? 1 : 0;
+		return 0;
+	case SG_GET_COMMAND_Q:
+		return put_user((int) sfp->cmd_q, ip);
+	case SG_SET_KEEP_ORPHAN:
+		result = get_user(val, ip);
+		if (result)
+			return result;
+		sfp->keep_orphan = val;
+		return 0;
+	case SG_GET_KEEP_ORPHAN:
+		return put_user((int) sfp->keep_orphan, ip);
+	case SG_NEXT_CMD_LEN:
+		result = get_user(val, ip);
+		if (result)
+			return result;
+		sfp->next_cmd_len = (val > 0) ? val : 0;
+		return 0;
+	case SG_GET_VERSION_NUM:
+		return put_user(sg_version_num, ip);
+	case SG_GET_ACCESS_COUNT:
+		/* faked - we don't have a real access count anymore */
+		val = (sdp->device ? 1 : 0);
+		return put_user(val, ip);
+	case SG_GET_REQUEST_TABLE:
+		if (!access_ok(VERIFY_WRITE, p, SZ_SG_REQ_INFO * SG_MAX_QUEUE))
+			return -EFAULT;
+		else {
+			sg_req_info_t *rinfo;
+			unsigned int ms;
+
+			rinfo = kmalloc(SZ_SG_REQ_INFO * SG_MAX_QUEUE,
+								GFP_KERNEL);
+			if (!rinfo)
+				return -ENOMEM;
+			read_lock_irqsave(&sfp->rq_list_lock, iflags);
+			for (srp = sfp->headrp, val = 0; val < SG_MAX_QUEUE;
+			     ++val, srp = srp ? srp->nextrp : srp) {
+				memset(&rinfo[val], 0, SZ_SG_REQ_INFO);
+				if (srp) {
+					rinfo[val].req_state = srp->done + 1;
+					rinfo[val].problem =
+					    srp->header.masked_status & 
+					    srp->header.host_status & 
+					    srp->header.driver_status;
+					if (srp->done)
+						rinfo[val].duration =
+							srp->header.duration;
+					else {
+						ms = jiffies_to_msecs(jiffies);
+						rinfo[val].duration =
+						    (ms > srp->header.duration) ?
+						    (ms - srp->header.duration) : 0;
+					}
+					rinfo[val].orphan = srp->orphan;
+					rinfo[val].sg_io_owned =
+							srp->sg_io_owned;
+					rinfo[val].pack_id =
+							srp->header.pack_id;
+					rinfo[val].usr_ptr =
+							srp->header.usr_ptr;
+				}
+			}
+			read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+			result = __copy_to_user(p, rinfo, 
+						SZ_SG_REQ_INFO * SG_MAX_QUEUE);
+			result = result ? -EFAULT : 0;
+			kfree(rinfo);
+			return result;
+		}
+	case SG_EMULATED_HOST:
+		if (atomic_read(&sdp->detaching))
+			return -ENODEV;
+		return put_user(sdp->device->host->hostt->emulated, ip);
+	case SCSI_IOCTL_SEND_COMMAND:
+		if (atomic_read(&sdp->detaching))
+			return -ENODEV;
+		if (read_only) {
+			unsigned char opcode = WRITE_6;
+			Scsi_Ioctl_Command __user *siocp = p;
+
+			if (copy_from_user(&opcode, siocp->data, 1))
+				return -EFAULT;
+			if (sg_allow_access(filp, &opcode))
+				return -EPERM;
+		}
+		return sg_scsi_ioctl(sdp->device->request_queue, NULL, filp->f_mode, p);
+	case SG_SET_DEBUG:
+		result = get_user(val, ip);
+		if (result)
+			return result;
+		sdp->sgdebug = (char) val;
+		return 0;
+	case BLKSECTGET:
+		return put_user(max_sectors_bytes(sdp->device->request_queue),
+				ip);
+	case BLKTRACESETUP:
+		return blk_trace_setup(sdp->device->request_queue,
+				       sdp->disk->disk_name,
+				       MKDEV(SCSI_GENERIC_MAJOR, sdp->index),
+				       NULL,
+				       (char *)arg);
+	case BLKTRACESTART:
+		return blk_trace_startstop(sdp->device->request_queue, 1);
+	case BLKTRACESTOP:
+		return blk_trace_startstop(sdp->device->request_queue, 0);
+	case BLKTRACETEARDOWN:
+		return blk_trace_remove(sdp->device->request_queue);
+	case SCSI_IOCTL_GET_IDLUN:
+	case SCSI_IOCTL_GET_BUS_NUMBER:
+	case SCSI_IOCTL_PROBE_HOST:
+	case SG_GET_TRANSFORM:
+	case SG_SCSI_RESET:
+		if (atomic_read(&sdp->detaching))
+			return -ENODEV;
+		break;
+	default:
+		if (read_only)
+			return -EPERM;	/* don't know so take safe approach */
+		break;
+	}
+
+	result = scsi_ioctl_block_when_processing_errors(sdp->device,
+			cmd_in, filp->f_flags & O_NDELAY);
+	if (result)
+		return result;
+	return scsi_ioctl(sdp->device, cmd_in, p);
+}
+
+#ifdef CONFIG_COMPAT
+static long sg_compat_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
+{
+	Sg_device *sdp;
+	Sg_fd *sfp;
+	struct scsi_device *sdev;
+
+	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
+		return -ENXIO;
+
+	sdev = sdp->device;
+	if (sdev->host->hostt->compat_ioctl) { 
+		int ret;
+
+		ret = sdev->host->hostt->compat_ioctl(sdev, cmd_in, (void __user *)arg);
+
+		return ret;
+	}
+	
+	return -ENOIOCTLCMD;
+}
+#endif
+
+static unsigned int
+sg_poll(struct file *filp, poll_table * wait)
+{
+	unsigned int res = 0;
+	Sg_device *sdp;
+	Sg_fd *sfp;
+	Sg_request *srp;
+	int count = 0;
+	unsigned long iflags;
+
+	sfp = filp->private_data;
+	if (!sfp)
+		return POLLERR;
+	sdp = sfp->parentdp;
+	if (!sdp)
+		return POLLERR;
+	poll_wait(filp, &sfp->read_wait, wait);
+	read_lock_irqsave(&sfp->rq_list_lock, iflags);
+	for (srp = sfp->headrp; srp; srp = srp->nextrp) {
+		/* if any read waiting, flag it */
+		if ((0 == res) && (1 == srp->done) && (!srp->sg_io_owned))
+			res = POLLIN | POLLRDNORM;
+		++count;
+	}
+	read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+
+	if (atomic_read(&sdp->detaching))
+		res |= POLLHUP;
+	else if (!sfp->cmd_q) {
+		if (0 == count)
+			res |= POLLOUT | POLLWRNORM;
+	} else if (count < SG_MAX_QUEUE)
+		res |= POLLOUT | POLLWRNORM;
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				      "sg_poll: res=0x%x\n", (int) res));
+	return res;
+}
+
+static int
+sg_fasync(int fd, struct file *filp, int mode)
+{
+	Sg_device *sdp;
+	Sg_fd *sfp;
+
+	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
+		return -ENXIO;
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				      "sg_fasync: mode=%d\n", mode));
+
+	return fasync_helper(fd, filp, mode, &sfp->async_qp);
+}
+
+static int
+sg_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	Sg_fd *sfp;
+	unsigned long offset, len, sa;
+	Sg_scatter_hold *rsv_schp;
+	int k, length;
+
+	if ((NULL == vma) || (!(sfp = (Sg_fd *) vma->vm_private_data)))
+		return VM_FAULT_SIGBUS;
+	rsv_schp = &sfp->reserve;
+	offset = vmf->pgoff << PAGE_SHIFT;
+	if (offset >= rsv_schp->bufflen)
+		return VM_FAULT_SIGBUS;
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp,
+				      "sg_vma_fault: offset=%lu, scatg=%d\n",
+				      offset, rsv_schp->k_use_sg));
+	sa = vma->vm_start;
+	length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
+	for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) {
+		len = vma->vm_end - sa;
+		len = (len < length) ? len : length;
+		if (offset < len) {
+			struct page *page = nth_page(rsv_schp->pages[k],
+						     offset >> PAGE_SHIFT);
+			get_page(page);	/* increment page count */
+			vmf->page = page;
+			return 0; /* success */
+		}
+		sa += len;
+		offset -= len;
+	}
+
+	return VM_FAULT_SIGBUS;
+}
+
+static const struct vm_operations_struct sg_mmap_vm_ops = {
+	.fault = sg_vma_fault,
+};
+
+static int
+sg_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	Sg_fd *sfp;
+	unsigned long req_sz, len, sa;
+	Sg_scatter_hold *rsv_schp;
+	int k, length;
+
+	if ((!filp) || (!vma) || (!(sfp = (Sg_fd *) filp->private_data)))
+		return -ENXIO;
+	req_sz = vma->vm_end - vma->vm_start;
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp,
+				      "sg_mmap starting, vm_start=%p, len=%d\n",
+				      (void *) vma->vm_start, (int) req_sz));
+	if (vma->vm_pgoff)
+		return -EINVAL;	/* want no offset */
+	rsv_schp = &sfp->reserve;
+	if (req_sz > rsv_schp->bufflen)
+		return -ENOMEM;	/* cannot map more than reserved buffer */
+
+	sa = vma->vm_start;
+	length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
+	for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) {
+		len = vma->vm_end - sa;
+		len = (len < length) ? len : length;
+		sa += len;
+	}
+
+	sfp->mmap_called = 1;
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_private_data = sfp;
+	vma->vm_ops = &sg_mmap_vm_ops;
+	return 0;
+}
+
+static void
+sg_rq_end_io_usercontext(struct work_struct *work)
+{
+	struct sg_request *srp = container_of(work, struct sg_request, ew.work);
+	struct sg_fd *sfp = srp->parentfp;
+
+	sg_finish_rem_req(srp);
+	kref_put(&sfp->f_ref, sg_remove_sfp);
+}
+
+/*
+ * This function is a "bottom half" handler that is called by the mid
+ * level when a command is completed (or has failed).
+ */
+static void
+sg_rq_end_io(struct request *rq, int uptodate)
+{
+	struct sg_request *srp = rq->end_io_data;
+	Sg_device *sdp;
+	Sg_fd *sfp;
+	unsigned long iflags;
+	unsigned int ms;
+	char *sense;
+	int result, resid, done = 1;
+
+	if (WARN_ON(srp->done != 0))
+		return;
+
+	sfp = srp->parentfp;
+	if (WARN_ON(sfp == NULL))
+		return;
+
+	sdp = sfp->parentdp;
+	if (unlikely(atomic_read(&sdp->detaching)))
+		pr_info("%s: device detaching\n", __func__);
+
+	sense = rq->sense;
+	result = rq->errors;
+	resid = rq->resid_len;
+
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sdp,
+				      "sg_cmd_done: pack_id=%d, res=0x%x\n",
+				      srp->header.pack_id, result));
+	srp->header.resid = resid;
+	ms = jiffies_to_msecs(jiffies);
+	srp->header.duration = (ms > srp->header.duration) ?
+				(ms - srp->header.duration) : 0;
+	if (0 != result) {
+		struct scsi_sense_hdr sshdr;
+
+		srp->header.status = 0xff & result;
+		srp->header.masked_status = status_byte(result);
+		srp->header.msg_status = msg_byte(result);
+		srp->header.host_status = host_byte(result);
+		srp->header.driver_status = driver_byte(result);
+		if ((sdp->sgdebug > 0) &&
+		    ((CHECK_CONDITION == srp->header.masked_status) ||
+		     (COMMAND_TERMINATED == srp->header.masked_status)))
+			__scsi_print_sense(sdp->device, __func__, sense,
+					   SCSI_SENSE_BUFFERSIZE);
+
+		/* Following if statement is a patch supplied by Eric Youngdale */
+		if (driver_byte(result) != 0
+		    && scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, &sshdr)
+		    && !scsi_sense_is_deferred(&sshdr)
+		    && sshdr.sense_key == UNIT_ATTENTION
+		    && sdp->device->removable) {
+			/* Detected possible disc change. Set the bit - this */
+			/* may be used if there are filesystems using this device */
+			sdp->device->changed = 1;
+		}
+	}
+	/* Rely on write phase to clean out srp status values, so no "else" */
+
+	/*
+	 * Free the request as soon as it is complete so that its resources
+	 * can be reused without waiting for userspace to read() the
+	 * result.  But keep the associated bio (if any) around until
+	 * blk_rq_unmap_user() can be called from user context.
+	 */
+	srp->rq = NULL;
+	if (rq->cmd != rq->__cmd)
+		kfree(rq->cmd);
+	__blk_put_request(rq->q, rq);
+
+	write_lock_irqsave(&sfp->rq_list_lock, iflags);
+	if (unlikely(srp->orphan)) {
+		if (sfp->keep_orphan)
+			srp->sg_io_owned = 0;
+		else
+			done = 0;
+	}
+	srp->done = done;
+	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+
+	if (likely(done)) {
+		/* Now wake up any sg_read() that is waiting for this
+		 * packet.
+		 */
+		wake_up_interruptible(&sfp->read_wait);
+		kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
+		kref_put(&sfp->f_ref, sg_remove_sfp);
+	} else {
+		INIT_WORK(&srp->ew.work, sg_rq_end_io_usercontext);
+		schedule_work(&srp->ew.work);
+	}
+}
+
+static const struct file_operations sg_fops = {
+	.owner = THIS_MODULE,
+	.read = sg_read,
+	.write = sg_write,
+	.poll = sg_poll,
+	.unlocked_ioctl = sg_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = sg_compat_ioctl,
+#endif
+	.open = sg_open,
+	.mmap = sg_mmap,
+	.release = sg_release,
+	.fasync = sg_fasync,
+	.llseek = no_llseek,
+};
+
+static struct class *sg_sysfs_class;
+
+static int sg_sysfs_valid = 0;
+
+static Sg_device *
+sg_alloc(struct gendisk *disk, struct scsi_device *scsidp)
+{
+	struct request_queue *q = scsidp->request_queue;
+	Sg_device *sdp;
+	unsigned long iflags;
+	int error;
+	u32 k;
+
+	sdp = kzalloc(sizeof(Sg_device), GFP_KERNEL);
+	if (!sdp) {
+		sdev_printk(KERN_WARNING, scsidp, "%s: kmalloc Sg_device "
+			    "failure\n", __func__);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	idr_preload(GFP_KERNEL);
+	write_lock_irqsave(&sg_index_lock, iflags);
+
+	error = idr_alloc(&sg_index_idr, sdp, 0, SG_MAX_DEVS, GFP_NOWAIT);
+	if (error < 0) {
+		if (error == -ENOSPC) {
+			sdev_printk(KERN_WARNING, scsidp,
+				    "Unable to attach sg device type=%d, minor number exceeds %d\n",
+				    scsidp->type, SG_MAX_DEVS - 1);
+			error = -ENODEV;
+		} else {
+			sdev_printk(KERN_WARNING, scsidp, "%s: idr "
+				    "allocation Sg_device failure: %d\n",
+				    __func__, error);
+		}
+		goto out_unlock;
+	}
+	k = error;
+
+	SCSI_LOG_TIMEOUT(3, sdev_printk(KERN_INFO, scsidp,
+					"sg_alloc: dev=%d \n", k));
+	sprintf(disk->disk_name, "sg%d", k);
+	disk->first_minor = k;
+	sdp->disk = disk;
+	sdp->device = scsidp;
+	mutex_init(&sdp->open_rel_lock);
+	INIT_LIST_HEAD(&sdp->sfds);
+	init_waitqueue_head(&sdp->open_wait);
+	atomic_set(&sdp->detaching, 0);
+	rwlock_init(&sdp->sfd_lock);
+	sdp->sg_tablesize = queue_max_segments(q);
+	sdp->index = k;
+	kref_init(&sdp->d_ref);
+	error = 0;
+
+out_unlock:
+	write_unlock_irqrestore(&sg_index_lock, iflags);
+	idr_preload_end();
+
+	if (error) {
+		kfree(sdp);
+		return ERR_PTR(error);
+	}
+	return sdp;
+}
+
+static int
+sg_add_device(struct device *cl_dev, struct class_interface *cl_intf)
+{
+	struct scsi_device *scsidp = to_scsi_device(cl_dev->parent);
+	struct gendisk *disk;
+	Sg_device *sdp = NULL;
+	struct cdev * cdev = NULL;
+	int error;
+	unsigned long iflags;
+
+	disk = alloc_disk(1);
+	if (!disk) {
+		pr_warn("%s: alloc_disk failed\n", __func__);
+		return -ENOMEM;
+	}
+	disk->major = SCSI_GENERIC_MAJOR;
+
+	error = -ENOMEM;
+	cdev = cdev_alloc();
+	if (!cdev) {
+		pr_warn("%s: cdev_alloc failed\n", __func__);
+		goto out;
+	}
+	cdev->owner = THIS_MODULE;
+	cdev->ops = &sg_fops;
+
+	sdp = sg_alloc(disk, scsidp);
+	if (IS_ERR(sdp)) {
+		pr_warn("%s: sg_alloc failed\n", __func__);
+		error = PTR_ERR(sdp);
+		goto out;
+	}
+
+	error = cdev_add(cdev, MKDEV(SCSI_GENERIC_MAJOR, sdp->index), 1);
+	if (error)
+		goto cdev_add_err;
+
+	sdp->cdev = cdev;
+	if (sg_sysfs_valid) {
+		struct device *sg_class_member;
+
+		sg_class_member = device_create(sg_sysfs_class, cl_dev->parent,
+						MKDEV(SCSI_GENERIC_MAJOR,
+						      sdp->index),
+						sdp, "%s", disk->disk_name);
+		if (IS_ERR(sg_class_member)) {
+			pr_err("%s: device_create failed\n", __func__);
+			error = PTR_ERR(sg_class_member);
+			goto cdev_add_err;
+		}
+		error = sysfs_create_link(&scsidp->sdev_gendev.kobj,
+					  &sg_class_member->kobj, "generic");
+		if (error)
+			pr_err("%s: unable to make symlink 'generic' back "
+			       "to sg%d\n", __func__, sdp->index);
+	} else
+		pr_warn("%s: sg_sys Invalid\n", __func__);
+
+	sdev_printk(KERN_NOTICE, scsidp, "Attached scsi generic sg%d "
+		    "type %d\n", sdp->index, scsidp->type);
+
+	dev_set_drvdata(cl_dev, sdp);
+
+	return 0;
+
+cdev_add_err:
+	write_lock_irqsave(&sg_index_lock, iflags);
+	idr_remove(&sg_index_idr, sdp->index);
+	write_unlock_irqrestore(&sg_index_lock, iflags);
+	kfree(sdp);
+
+out:
+	put_disk(disk);
+	if (cdev)
+		cdev_del(cdev);
+	return error;
+}
+
+static void
+sg_device_destroy(struct kref *kref)
+{
+	struct sg_device *sdp = container_of(kref, struct sg_device, d_ref);
+	unsigned long flags;
+
+	/* CAUTION!  Note that the device can still be found via idr_find()
+	 * even though the refcount is 0.  Therefore, do idr_remove() BEFORE
+	 * any other cleanup.
+	 */
+
+	write_lock_irqsave(&sg_index_lock, flags);
+	idr_remove(&sg_index_idr, sdp->index);
+	write_unlock_irqrestore(&sg_index_lock, flags);
+
+	SCSI_LOG_TIMEOUT(3,
+		sg_printk(KERN_INFO, sdp, "sg_device_destroy\n"));
+
+	put_disk(sdp->disk);
+	kfree(sdp);
+}
+
+static void
+sg_remove_device(struct device *cl_dev, struct class_interface *cl_intf)
+{
+	struct scsi_device *scsidp = to_scsi_device(cl_dev->parent);
+	Sg_device *sdp = dev_get_drvdata(cl_dev);
+	unsigned long iflags;
+	Sg_fd *sfp;
+	int val;
+
+	if (!sdp)
+		return;
+	/* want sdp->detaching non-zero as soon as possible */
+	val = atomic_inc_return(&sdp->detaching);
+	if (val > 1)
+		return; /* only want to do following once per device */
+
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				      "%s\n", __func__));
+
+	read_lock_irqsave(&sdp->sfd_lock, iflags);
+	list_for_each_entry(sfp, &sdp->sfds, sfd_siblings) {
+		wake_up_interruptible_all(&sfp->read_wait);
+		kill_fasync(&sfp->async_qp, SIGPOLL, POLL_HUP);
+	}
+	wake_up_interruptible_all(&sdp->open_wait);
+	read_unlock_irqrestore(&sdp->sfd_lock, iflags);
+
+	sysfs_remove_link(&scsidp->sdev_gendev.kobj, "generic");
+	device_destroy(sg_sysfs_class, MKDEV(SCSI_GENERIC_MAJOR, sdp->index));
+	cdev_del(sdp->cdev);
+	sdp->cdev = NULL;
+
+	kref_put(&sdp->d_ref, sg_device_destroy);
+}
+
+module_param_named(scatter_elem_sz, scatter_elem_sz, int, S_IRUGO | S_IWUSR);
+module_param_named(def_reserved_size, def_reserved_size, int,
+		   S_IRUGO | S_IWUSR);
+module_param_named(allow_dio, sg_allow_dio, int, S_IRUGO | S_IWUSR);
+
+MODULE_AUTHOR("Douglas Gilbert");
+MODULE_DESCRIPTION("SCSI generic (sg) driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(SG_VERSION_STR);
+MODULE_ALIAS_CHARDEV_MAJOR(SCSI_GENERIC_MAJOR);
+
+MODULE_PARM_DESC(scatter_elem_sz, "scatter gather element "
+                "size (default: max(SG_SCATTER_SZ, PAGE_SIZE))");
+MODULE_PARM_DESC(def_reserved_size, "size of buffer reserved for each fd");
+MODULE_PARM_DESC(allow_dio, "allow direct I/O (default: 0 (disallow))");
+
+static int __init
+init_sg(void)
+{
+	int rc;
+
+	if (scatter_elem_sz < PAGE_SIZE) {
+		scatter_elem_sz = PAGE_SIZE;
+		scatter_elem_sz_prev = scatter_elem_sz;
+	}
+	if (def_reserved_size >= 0)
+		sg_big_buff = def_reserved_size;
+	else
+		def_reserved_size = sg_big_buff;
+
+	rc = register_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0), 
+				    SG_MAX_DEVS, "sg");
+	if (rc)
+		return rc;
+        sg_sysfs_class = class_create(THIS_MODULE, "scsi_generic");
+        if ( IS_ERR(sg_sysfs_class) ) {
+		rc = PTR_ERR(sg_sysfs_class);
+		goto err_out;
+        }
+	sg_sysfs_valid = 1;
+	rc = scsi_register_interface(&sg_interface);
+	if (0 == rc) {
+#ifdef CONFIG_SCSI_PROC_FS
+		sg_proc_init();
+#endif				/* CONFIG_SCSI_PROC_FS */
+		return 0;
+	}
+	class_destroy(sg_sysfs_class);
+err_out:
+	unregister_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0), SG_MAX_DEVS);
+	return rc;
+}
+
+static void __exit
+exit_sg(void)
+{
+#ifdef CONFIG_SCSI_PROC_FS
+	sg_proc_cleanup();
+#endif				/* CONFIG_SCSI_PROC_FS */
+	scsi_unregister_interface(&sg_interface);
+	class_destroy(sg_sysfs_class);
+	sg_sysfs_valid = 0;
+	unregister_chrdev_region(MKDEV(SCSI_GENERIC_MAJOR, 0),
+				 SG_MAX_DEVS);
+	idr_destroy(&sg_index_idr);
+}
+
+static int
+sg_start_req(Sg_request *srp, unsigned char *cmd)
+{
+	int res;
+	struct request *rq;
+	Sg_fd *sfp = srp->parentfp;
+	sg_io_hdr_t *hp = &srp->header;
+	int dxfer_len = (int) hp->dxfer_len;
+	int dxfer_dir = hp->dxfer_direction;
+	unsigned int iov_count = hp->iovec_count;
+	Sg_scatter_hold *req_schp = &srp->data;
+	Sg_scatter_hold *rsv_schp = &sfp->reserve;
+	struct request_queue *q = sfp->parentdp->device->request_queue;
+	struct rq_map_data *md, map_data;
+	int rw = hp->dxfer_direction == SG_DXFER_TO_DEV ? WRITE : READ;
+	unsigned char *long_cmdp = NULL;
+
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
+				      "sg_start_req: dxfer_len=%d\n",
+				      dxfer_len));
+
+	if (hp->cmd_len > BLK_MAX_CDB) {
+		long_cmdp = kzalloc(hp->cmd_len, GFP_KERNEL);
+		if (!long_cmdp)
+			return -ENOMEM;
+	}
+
+	/*
+	 * NOTE
+	 *
+	 * With scsi-mq enabled, there are a fixed number of preallocated
+	 * requests equal in number to shost->can_queue.  If all of the
+	 * preallocated requests are already in use, then using GFP_ATOMIC with
+	 * blk_get_request() will return -EWOULDBLOCK, whereas using GFP_KERNEL
+	 * will cause blk_get_request() to sleep until an active command
+	 * completes, freeing up a request.  Neither option is ideal, but
+	 * GFP_KERNEL is the better choice to prevent userspace from getting an
+	 * unexpected EWOULDBLOCK.
+	 *
+	 * With scsi-mq disabled, blk_get_request() with GFP_KERNEL usually
+	 * does not sleep except under memory pressure.
+	 */
+	rq = blk_get_request(q, rw, GFP_KERNEL);
+	if (IS_ERR(rq)) {
+		kfree(long_cmdp);
+		return PTR_ERR(rq);
+	}
+
+	blk_rq_set_block_pc(rq);
+
+	if (hp->cmd_len > BLK_MAX_CDB)
+		rq->cmd = long_cmdp;
+	memcpy(rq->cmd, cmd, hp->cmd_len);
+	rq->cmd_len = hp->cmd_len;
+
+	srp->rq = rq;
+	rq->end_io_data = srp;
+	rq->sense = srp->sense_b;
+	rq->retries = SG_DEFAULT_RETRIES;
+
+	if ((dxfer_len <= 0) || (dxfer_dir == SG_DXFER_NONE))
+		return 0;
+
+	if (sg_allow_dio && hp->flags & SG_FLAG_DIRECT_IO &&
+	    dxfer_dir != SG_DXFER_UNKNOWN && !iov_count &&
+	    !sfp->parentdp->device->host->unchecked_isa_dma &&
+	    blk_rq_aligned(q, (unsigned long)hp->dxferp, dxfer_len))
+		md = NULL;
+	else
+		md = &map_data;
+
+	if (md) {
+		if (!sg_res_in_use(sfp) && dxfer_len <= rsv_schp->bufflen)
+			sg_link_reserve(sfp, srp, dxfer_len);
+		else {
+			res = sg_build_indirect(req_schp, sfp, dxfer_len);
+			if (res)
+				return res;
+		}
+
+		md->pages = req_schp->pages;
+		md->page_order = req_schp->page_order;
+		md->nr_entries = req_schp->k_use_sg;
+		md->offset = 0;
+		md->null_mapped = hp->dxferp ? 0 : 1;
+		if (dxfer_dir == SG_DXFER_TO_FROM_DEV)
+			md->from_user = 1;
+		else
+			md->from_user = 0;
+	}
+
+	if (iov_count) {
+		struct iovec *iov = NULL;
+		struct iov_iter i;
+
+		res = import_iovec(rw, hp->dxferp, iov_count, 0, &iov, &i);
+		if (res < 0)
+			return res;
+
+		iov_iter_truncate(&i, hp->dxfer_len);
+
+		res = blk_rq_map_user_iov(q, rq, md, &i, GFP_ATOMIC);
+		kfree(iov);
+	} else
+		res = blk_rq_map_user(q, rq, md, hp->dxferp,
+				      hp->dxfer_len, GFP_ATOMIC);
+
+	if (!res) {
+		srp->bio = rq->bio;
+
+		if (!md) {
+			req_schp->dio_in_use = 1;
+			hp->info |= SG_INFO_DIRECT_IO;
+		}
+	}
+	return res;
+}
+
+static int
+sg_finish_rem_req(Sg_request *srp)
+{
+	int ret = 0;
+
+	Sg_fd *sfp = srp->parentfp;
+	Sg_scatter_hold *req_schp = &srp->data;
+
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
+				      "sg_finish_rem_req: res_used=%d\n",
+				      (int) srp->res_used));
+	if (srp->bio)
+		ret = blk_rq_unmap_user(srp->bio);
+
+	if (srp->rq) {
+		if (srp->rq->cmd != srp->rq->__cmd)
+			kfree(srp->rq->cmd);
+		blk_put_request(srp->rq);
+	}
+
+	if (srp->res_used)
+		sg_unlink_reserve(sfp, srp);
+	else
+		sg_remove_scat(sfp, req_schp);
+
+	sg_remove_request(sfp, srp);
+
+	return ret;
+}
+
+static int
+sg_build_sgat(Sg_scatter_hold * schp, const Sg_fd * sfp, int tablesize)
+{
+	int sg_bufflen = tablesize * sizeof(struct page *);
+	gfp_t gfp_flags = GFP_ATOMIC | __GFP_NOWARN;
+
+	schp->pages = kzalloc(sg_bufflen, gfp_flags);
+	if (!schp->pages)
+		return -ENOMEM;
+	schp->sglist_len = sg_bufflen;
+	return tablesize;	/* number of scat_gath elements allocated */
+}
+
+static int
+sg_build_indirect(Sg_scatter_hold * schp, Sg_fd * sfp, int buff_size)
+{
+	int ret_sz = 0, i, k, rem_sz, num, mx_sc_elems;
+	int sg_tablesize = sfp->parentdp->sg_tablesize;
+	int blk_size = buff_size, order;
+	gfp_t gfp_mask = GFP_ATOMIC | __GFP_COMP | __GFP_NOWARN;
+
+	if (blk_size < 0)
+		return -EFAULT;
+	if (0 == blk_size)
+		++blk_size;	/* don't know why */
+	/* round request up to next highest SG_SECTOR_SZ byte boundary */
+	blk_size = ALIGN(blk_size, SG_SECTOR_SZ);
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
+		"sg_build_indirect: buff_size=%d, blk_size=%d\n",
+		buff_size, blk_size));
+
+	/* N.B. ret_sz carried into this block ... */
+	mx_sc_elems = sg_build_sgat(schp, sfp, sg_tablesize);
+	if (mx_sc_elems < 0)
+		return mx_sc_elems;	/* most likely -ENOMEM */
+
+	num = scatter_elem_sz;
+	if (unlikely(num != scatter_elem_sz_prev)) {
+		if (num < PAGE_SIZE) {
+			scatter_elem_sz = PAGE_SIZE;
+			scatter_elem_sz_prev = PAGE_SIZE;
+		} else
+			scatter_elem_sz_prev = num;
+	}
+
+	if (sfp->low_dma)
+		gfp_mask |= GFP_DMA;
+
+	if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
+		gfp_mask |= __GFP_ZERO;
+
+	order = get_order(num);
+retry:
+	ret_sz = 1 << (PAGE_SHIFT + order);
+
+	for (k = 0, rem_sz = blk_size; rem_sz > 0 && k < mx_sc_elems;
+	     k++, rem_sz -= ret_sz) {
+
+		num = (rem_sz > scatter_elem_sz_prev) ?
+			scatter_elem_sz_prev : rem_sz;
+
+		schp->pages[k] = alloc_pages(gfp_mask, order);
+		if (!schp->pages[k])
+			goto out;
+
+		if (num == scatter_elem_sz_prev) {
+			if (unlikely(ret_sz > scatter_elem_sz_prev)) {
+				scatter_elem_sz = ret_sz;
+				scatter_elem_sz_prev = ret_sz;
+			}
+		}
+
+		SCSI_LOG_TIMEOUT(5, sg_printk(KERN_INFO, sfp->parentdp,
+				 "sg_build_indirect: k=%d, num=%d, ret_sz=%d\n",
+				 k, num, ret_sz));
+	}		/* end of for loop */
+
+	schp->page_order = order;
+	schp->k_use_sg = k;
+	SCSI_LOG_TIMEOUT(5, sg_printk(KERN_INFO, sfp->parentdp,
+			 "sg_build_indirect: k_use_sg=%d, rem_sz=%d\n",
+			 k, rem_sz));
+
+	schp->bufflen = blk_size;
+	if (rem_sz > 0)	/* must have failed */
+		return -ENOMEM;
+	return 0;
+out:
+	for (i = 0; i < k; i++)
+		__free_pages(schp->pages[i], order);
+
+	if (--order >= 0)
+		goto retry;
+
+	return -ENOMEM;
+}
+
+static void
+sg_remove_scat(Sg_fd * sfp, Sg_scatter_hold * schp)
+{
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
+			 "sg_remove_scat: k_use_sg=%d\n", schp->k_use_sg));
+	if (schp->pages && schp->sglist_len > 0) {
+		if (!schp->dio_in_use) {
+			int k;
+
+			for (k = 0; k < schp->k_use_sg && schp->pages[k]; k++) {
+				SCSI_LOG_TIMEOUT(5,
+					sg_printk(KERN_INFO, sfp->parentdp,
+					"sg_remove_scat: k=%d, pg=0x%p\n",
+					k, schp->pages[k]));
+				__free_pages(schp->pages[k], schp->page_order);
+			}
+
+			kfree(schp->pages);
+		}
+	}
+	memset(schp, 0, sizeof (*schp));
+}
+
+static int
+sg_read_oxfer(Sg_request * srp, char __user *outp, int num_read_xfer)
+{
+	Sg_scatter_hold *schp = &srp->data;
+	int k, num;
+
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, srp->parentfp->parentdp,
+			 "sg_read_oxfer: num_read_xfer=%d\n",
+			 num_read_xfer));
+	if ((!outp) || (num_read_xfer <= 0))
+		return 0;
+
+	num = 1 << (PAGE_SHIFT + schp->page_order);
+	for (k = 0; k < schp->k_use_sg && schp->pages[k]; k++) {
+		if (num > num_read_xfer) {
+			if (__copy_to_user(outp, page_address(schp->pages[k]),
+					   num_read_xfer))
+				return -EFAULT;
+			break;
+		} else {
+			if (__copy_to_user(outp, page_address(schp->pages[k]),
+					   num))
+				return -EFAULT;
+			num_read_xfer -= num;
+			if (num_read_xfer <= 0)
+				break;
+			outp += num;
+		}
+	}
+
+	return 0;
+}
+
+static void
+sg_build_reserve(Sg_fd * sfp, int req_size)
+{
+	Sg_scatter_hold *schp = &sfp->reserve;
+
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
+			 "sg_build_reserve: req_size=%d\n", req_size));
+	do {
+		if (req_size < PAGE_SIZE)
+			req_size = PAGE_SIZE;
+		if (0 == sg_build_indirect(schp, sfp, req_size))
+			return;
+		else
+			sg_remove_scat(sfp, schp);
+		req_size >>= 1;	/* divide by 2 */
+	} while (req_size > (PAGE_SIZE / 2));
+}
+
+static void
+sg_link_reserve(Sg_fd * sfp, Sg_request * srp, int size)
+{
+	Sg_scatter_hold *req_schp = &srp->data;
+	Sg_scatter_hold *rsv_schp = &sfp->reserve;
+	int k, num, rem;
+
+	srp->res_used = 1;
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sfp->parentdp,
+			 "sg_link_reserve: size=%d\n", size));
+	rem = size;
+
+	num = 1 << (PAGE_SHIFT + rsv_schp->page_order);
+	for (k = 0; k < rsv_schp->k_use_sg; k++) {
+		if (rem <= num) {
+			req_schp->k_use_sg = k + 1;
+			req_schp->sglist_len = rsv_schp->sglist_len;
+			req_schp->pages = rsv_schp->pages;
+
+			req_schp->bufflen = size;
+			req_schp->page_order = rsv_schp->page_order;
+			break;
+		} else
+			rem -= num;
+	}
+
+	if (k >= rsv_schp->k_use_sg)
+		SCSI_LOG_TIMEOUT(1, sg_printk(KERN_INFO, sfp->parentdp,
+				 "sg_link_reserve: BAD size\n"));
+}
+
+static void
+sg_unlink_reserve(Sg_fd * sfp, Sg_request * srp)
+{
+	Sg_scatter_hold *req_schp = &srp->data;
+
+	SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, srp->parentfp->parentdp,
+				      "sg_unlink_reserve: req->k_use_sg=%d\n",
+				      (int) req_schp->k_use_sg));
+	req_schp->k_use_sg = 0;
+	req_schp->bufflen = 0;
+	req_schp->pages = NULL;
+	req_schp->page_order = 0;
+	req_schp->sglist_len = 0;
+	sfp->save_scat_len = 0;
+	srp->res_used = 0;
+}
+
+static Sg_request *
+sg_get_rq_mark(Sg_fd * sfp, int pack_id)
+{
+	Sg_request *resp;
+	unsigned long iflags;
+
+	write_lock_irqsave(&sfp->rq_list_lock, iflags);
+	for (resp = sfp->headrp; resp; resp = resp->nextrp) {
+		/* look for requests that are ready + not SG_IO owned */
+		if ((1 == resp->done) && (!resp->sg_io_owned) &&
+		    ((-1 == pack_id) || (resp->header.pack_id == pack_id))) {
+			resp->done = 2;	/* guard against other readers */
+			break;
+		}
+	}
+	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+	return resp;
+}
+
+/* always adds to end of list */
+static Sg_request *
+sg_add_request(Sg_fd * sfp)
+{
+	int k;
+	unsigned long iflags;
+	Sg_request *resp;
+	Sg_request *rp = sfp->req_arr;
+
+	write_lock_irqsave(&sfp->rq_list_lock, iflags);
+	resp = sfp->headrp;
+	if (!resp) {
+		memset(rp, 0, sizeof (Sg_request));
+		rp->parentfp = sfp;
+		resp = rp;
+		sfp->headrp = resp;
+	} else {
+		if (0 == sfp->cmd_q)
+			resp = NULL;	/* command queuing disallowed */
+		else {
+			for (k = 0; k < SG_MAX_QUEUE; ++k, ++rp) {
+				if (!rp->parentfp)
+					break;
+			}
+			if (k < SG_MAX_QUEUE) {
+				memset(rp, 0, sizeof (Sg_request));
+				rp->parentfp = sfp;
+				while (resp->nextrp)
+					resp = resp->nextrp;
+				resp->nextrp = rp;
+				resp = rp;
+			} else
+				resp = NULL;
+		}
+	}
+	if (resp) {
+		resp->nextrp = NULL;
+		resp->header.duration = jiffies_to_msecs(jiffies);
+	}
+	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+	return resp;
+}
+
+/* Return of 1 for found; 0 for not found */
+static int
+sg_remove_request(Sg_fd * sfp, Sg_request * srp)
+{
+	Sg_request *prev_rp;
+	Sg_request *rp;
+	unsigned long iflags;
+	int res = 0;
+
+	if ((!sfp) || (!srp) || (!sfp->headrp))
+		return res;
+	write_lock_irqsave(&sfp->rq_list_lock, iflags);
+	prev_rp = sfp->headrp;
+	if (srp == prev_rp) {
+		sfp->headrp = prev_rp->nextrp;
+		prev_rp->parentfp = NULL;
+		res = 1;
+	} else {
+		while ((rp = prev_rp->nextrp)) {
+			if (srp == rp) {
+				prev_rp->nextrp = rp->nextrp;
+				rp->parentfp = NULL;
+				res = 1;
+				break;
+			}
+			prev_rp = rp;
+		}
+	}
+	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+	return res;
+}
+
+static Sg_fd *
+sg_add_sfp(Sg_device * sdp)
+{
+	Sg_fd *sfp;
+	unsigned long iflags;
+	int bufflen;
+
+	sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN);
+	if (!sfp)
+		return ERR_PTR(-ENOMEM);
+
+	init_waitqueue_head(&sfp->read_wait);
+	rwlock_init(&sfp->rq_list_lock);
+
+	kref_init(&sfp->f_ref);
+	sfp->timeout = SG_DEFAULT_TIMEOUT;
+	sfp->timeout_user = SG_DEFAULT_TIMEOUT_USER;
+	sfp->force_packid = SG_DEF_FORCE_PACK_ID;
+	sfp->low_dma = (SG_DEF_FORCE_LOW_DMA == 0) ?
+	    sdp->device->host->unchecked_isa_dma : 1;
+	sfp->cmd_q = SG_DEF_COMMAND_Q;
+	sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
+	sfp->parentdp = sdp;
+	write_lock_irqsave(&sdp->sfd_lock, iflags);
+	if (atomic_read(&sdp->detaching)) {
+		write_unlock_irqrestore(&sdp->sfd_lock, iflags);
+		return ERR_PTR(-ENODEV);
+	}
+	list_add_tail(&sfp->sfd_siblings, &sdp->sfds);
+	write_unlock_irqrestore(&sdp->sfd_lock, iflags);
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				      "sg_add_sfp: sfp=0x%p\n", sfp));
+	if (unlikely(sg_big_buff != def_reserved_size))
+		sg_big_buff = def_reserved_size;
+
+	bufflen = min_t(int, sg_big_buff,
+			max_sectors_bytes(sdp->device->request_queue));
+	sg_build_reserve(sfp, bufflen);
+	SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp,
+				      "sg_add_sfp: bufflen=%d, k_use_sg=%d\n",
+				      sfp->reserve.bufflen,
+				      sfp->reserve.k_use_sg));
+
+	kref_get(&sdp->d_ref);
+	__module_get(THIS_MODULE);
+	return sfp;
+}
+
+static void
+sg_remove_sfp_usercontext(struct work_struct *work)
+{
+	struct sg_fd *sfp = container_of(work, struct sg_fd, ew.work);
+	struct sg_device *sdp = sfp->parentdp;
+
+	/* Cleanup any responses which were never read(). */
+	while (sfp->headrp)
+		sg_finish_rem_req(sfp->headrp);
+
+	if (sfp->reserve.bufflen > 0) {
+		SCSI_LOG_TIMEOUT(6, sg_printk(KERN_INFO, sdp,
+				"sg_remove_sfp:    bufflen=%d, k_use_sg=%d\n",
+				(int) sfp->reserve.bufflen,
+				(int) sfp->reserve.k_use_sg));
+		sg_remove_scat(sfp, &sfp->reserve);
+	}
+
+	SCSI_LOG_TIMEOUT(6, sg_printk(KERN_INFO, sdp,
+			"sg_remove_sfp: sfp=0x%p\n", sfp));
+	kfree(sfp);
+
+	scsi_device_put(sdp->device);
+	kref_put(&sdp->d_ref, sg_device_destroy);
+	module_put(THIS_MODULE);
+}
+
+static void
+sg_remove_sfp(struct kref *kref)
+{
+	struct sg_fd *sfp = container_of(kref, struct sg_fd, f_ref);
+	struct sg_device *sdp = sfp->parentdp;
+	unsigned long iflags;
+
+	write_lock_irqsave(&sdp->sfd_lock, iflags);
+	list_del(&sfp->sfd_siblings);
+	write_unlock_irqrestore(&sdp->sfd_lock, iflags);
+
+	INIT_WORK(&sfp->ew.work, sg_remove_sfp_usercontext);
+	schedule_work(&sfp->ew.work);
+}
+
+static int
+sg_res_in_use(Sg_fd * sfp)
+{
+	const Sg_request *srp;
+	unsigned long iflags;
+
+	read_lock_irqsave(&sfp->rq_list_lock, iflags);
+	for (srp = sfp->headrp; srp; srp = srp->nextrp)
+		if (srp->res_used)
+			break;
+	read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+	return srp ? 1 : 0;
+}
+
+#ifdef CONFIG_SCSI_PROC_FS
+static int
+sg_idr_max_id(int id, void *p, void *data)
+{
+	int *k = data;
+
+	if (*k < id)
+		*k = id;
+
+	return 0;
+}
+
+static int
+sg_last_dev(void)
+{
+	int k = -1;
+	unsigned long iflags;
+
+	read_lock_irqsave(&sg_index_lock, iflags);
+	idr_for_each(&sg_index_idr, sg_idr_max_id, &k);
+	read_unlock_irqrestore(&sg_index_lock, iflags);
+	return k + 1;		/* origin 1 */
+}
+#endif
+
+/* must be called with sg_index_lock held */
+static Sg_device *sg_lookup_dev(int dev)
+{
+	return idr_find(&sg_index_idr, dev);
+}
+
+static Sg_device *
+sg_get_dev(int dev)
+{
+	struct sg_device *sdp;
+	unsigned long flags;
+
+	read_lock_irqsave(&sg_index_lock, flags);
+	sdp = sg_lookup_dev(dev);
+	if (!sdp)
+		sdp = ERR_PTR(-ENXIO);
+	else if (atomic_read(&sdp->detaching)) {
+		/* If sdp->detaching, then the refcount may already be 0, in
+		 * which case it would be a bug to do kref_get().
+		 */
+		sdp = ERR_PTR(-ENODEV);
+	} else
+		kref_get(&sdp->d_ref);
+	read_unlock_irqrestore(&sg_index_lock, flags);
+
+	return sdp;
+}
+
+#ifdef CONFIG_SCSI_PROC_FS
+
+static struct proc_dir_entry *sg_proc_sgp = NULL;
+
+static char sg_proc_sg_dirname[] = "scsi/sg";
+
+static int sg_proc_seq_show_int(struct seq_file *s, void *v);
+
+static int sg_proc_single_open_adio(struct inode *inode, struct file *file);
+static ssize_t sg_proc_write_adio(struct file *filp, const char __user *buffer,
+			          size_t count, loff_t *off);
+static const struct file_operations adio_fops = {
+	.owner = THIS_MODULE,
+	.open = sg_proc_single_open_adio,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.write = sg_proc_write_adio,
+	.release = single_release,
+};
+
+static int sg_proc_single_open_dressz(struct inode *inode, struct file *file);
+static ssize_t sg_proc_write_dressz(struct file *filp, 
+		const char __user *buffer, size_t count, loff_t *off);
+static const struct file_operations dressz_fops = {
+	.owner = THIS_MODULE,
+	.open = sg_proc_single_open_dressz,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.write = sg_proc_write_dressz,
+	.release = single_release,
+};
+
+static int sg_proc_seq_show_version(struct seq_file *s, void *v);
+static int sg_proc_single_open_version(struct inode *inode, struct file *file);
+static const struct file_operations version_fops = {
+	.owner = THIS_MODULE,
+	.open = sg_proc_single_open_version,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int sg_proc_seq_show_devhdr(struct seq_file *s, void *v);
+static int sg_proc_single_open_devhdr(struct inode *inode, struct file *file);
+static const struct file_operations devhdr_fops = {
+	.owner = THIS_MODULE,
+	.open = sg_proc_single_open_devhdr,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int sg_proc_seq_show_dev(struct seq_file *s, void *v);
+static int sg_proc_open_dev(struct inode *inode, struct file *file);
+static void * dev_seq_start(struct seq_file *s, loff_t *pos);
+static void * dev_seq_next(struct seq_file *s, void *v, loff_t *pos);
+static void dev_seq_stop(struct seq_file *s, void *v);
+static const struct file_operations dev_fops = {
+	.owner = THIS_MODULE,
+	.open = sg_proc_open_dev,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+static const struct seq_operations dev_seq_ops = {
+	.start = dev_seq_start,
+	.next  = dev_seq_next,
+	.stop  = dev_seq_stop,
+	.show  = sg_proc_seq_show_dev,
+};
+
+static int sg_proc_seq_show_devstrs(struct seq_file *s, void *v);
+static int sg_proc_open_devstrs(struct inode *inode, struct file *file);
+static const struct file_operations devstrs_fops = {
+	.owner = THIS_MODULE,
+	.open = sg_proc_open_devstrs,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+static const struct seq_operations devstrs_seq_ops = {
+	.start = dev_seq_start,
+	.next  = dev_seq_next,
+	.stop  = dev_seq_stop,
+	.show  = sg_proc_seq_show_devstrs,
+};
+
+static int sg_proc_seq_show_debug(struct seq_file *s, void *v);
+static int sg_proc_open_debug(struct inode *inode, struct file *file);
+static const struct file_operations debug_fops = {
+	.owner = THIS_MODULE,
+	.open = sg_proc_open_debug,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+static const struct seq_operations debug_seq_ops = {
+	.start = dev_seq_start,
+	.next  = dev_seq_next,
+	.stop  = dev_seq_stop,
+	.show  = sg_proc_seq_show_debug,
+};
+
+
+struct sg_proc_leaf {
+	const char * name;
+	const struct file_operations * fops;
+};
+
+static const struct sg_proc_leaf sg_proc_leaf_arr[] = {
+	{"allow_dio", &adio_fops},
+	{"debug", &debug_fops},
+	{"def_reserved_size", &dressz_fops},
+	{"device_hdr", &devhdr_fops},
+	{"devices", &dev_fops},
+	{"device_strs", &devstrs_fops},
+	{"version", &version_fops}
+};
+
+static int
+sg_proc_init(void)
+{
+	int num_leaves = ARRAY_SIZE(sg_proc_leaf_arr);
+	int k;
+
+	sg_proc_sgp = proc_mkdir(sg_proc_sg_dirname, NULL);
+	if (!sg_proc_sgp)
+		return 1;
+	for (k = 0; k < num_leaves; ++k) {
+		const struct sg_proc_leaf *leaf = &sg_proc_leaf_arr[k];
+		umode_t mask = leaf->fops->write ? S_IRUGO | S_IWUSR : S_IRUGO;
+		proc_create(leaf->name, mask, sg_proc_sgp, leaf->fops);
+	}
+	return 0;
+}
+
+static void
+sg_proc_cleanup(void)
+{
+	int k;
+	int num_leaves = ARRAY_SIZE(sg_proc_leaf_arr);
+
+	if (!sg_proc_sgp)
+		return;
+	for (k = 0; k < num_leaves; ++k)
+		remove_proc_entry(sg_proc_leaf_arr[k].name, sg_proc_sgp);
+	remove_proc_entry(sg_proc_sg_dirname, NULL);
+}
+
+
+static int sg_proc_seq_show_int(struct seq_file *s, void *v)
+{
+	seq_printf(s, "%d\n", *((int *)s->private));
+	return 0;
+}
+
+static int sg_proc_single_open_adio(struct inode *inode, struct file *file)
+{
+	return single_open(file, sg_proc_seq_show_int, &sg_allow_dio);
+}
+
+static ssize_t 
+sg_proc_write_adio(struct file *filp, const char __user *buffer,
+		   size_t count, loff_t *off)
+{
+	int err;
+	unsigned long num;
+
+	if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
+		return -EACCES;
+	err = kstrtoul_from_user(buffer, count, 0, &num);
+	if (err)
+		return err;
+	sg_allow_dio = num ? 1 : 0;
+	return count;
+}
+
+static int sg_proc_single_open_dressz(struct inode *inode, struct file *file)
+{
+	return single_open(file, sg_proc_seq_show_int, &sg_big_buff);
+}
+
+static ssize_t 
+sg_proc_write_dressz(struct file *filp, const char __user *buffer,
+		     size_t count, loff_t *off)
+{
+	int err;
+	unsigned long k = ULONG_MAX;
+
+	if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
+		return -EACCES;
+
+	err = kstrtoul_from_user(buffer, count, 0, &k);
+	if (err)
+		return err;
+	if (k <= 1048576) {	/* limit "big buff" to 1 MB */
+		sg_big_buff = k;
+		return count;
+	}
+	return -ERANGE;
+}
+
+static int sg_proc_seq_show_version(struct seq_file *s, void *v)
+{
+	seq_printf(s, "%d\t%s [%s]\n", sg_version_num, SG_VERSION_STR,
+		   sg_version_date);
+	return 0;
+}
+
+static int sg_proc_single_open_version(struct inode *inode, struct file *file)
+{
+	return single_open(file, sg_proc_seq_show_version, NULL);
+}
+
+static int sg_proc_seq_show_devhdr(struct seq_file *s, void *v)
+{
+	seq_puts(s, "host\tchan\tid\tlun\ttype\topens\tqdepth\tbusy\tonline\n");
+	return 0;
+}
+
+static int sg_proc_single_open_devhdr(struct inode *inode, struct file *file)
+{
+	return single_open(file, sg_proc_seq_show_devhdr, NULL);
+}
+
+struct sg_proc_deviter {
+	loff_t	index;
+	size_t	max;
+};
+
+static void * dev_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct sg_proc_deviter * it = kmalloc(sizeof(*it), GFP_KERNEL);
+
+	s->private = it;
+	if (! it)
+		return NULL;
+
+	it->index = *pos;
+	it->max = sg_last_dev();
+	if (it->index >= it->max)
+		return NULL;
+	return it;
+}
+
+static void * dev_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct sg_proc_deviter * it = s->private;
+
+	*pos = ++it->index;
+	return (it->index < it->max) ? it : NULL;
+}
+
+static void dev_seq_stop(struct seq_file *s, void *v)
+{
+	kfree(s->private);
+}
+
+static int sg_proc_open_dev(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &dev_seq_ops);
+}
+
+static int sg_proc_seq_show_dev(struct seq_file *s, void *v)
+{
+	struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
+	Sg_device *sdp;
+	struct scsi_device *scsidp;
+	unsigned long iflags;
+
+	read_lock_irqsave(&sg_index_lock, iflags);
+	sdp = it ? sg_lookup_dev(it->index) : NULL;
+	if ((NULL == sdp) || (NULL == sdp->device) ||
+	    (atomic_read(&sdp->detaching)))
+		seq_puts(s, "-1\t-1\t-1\t-1\t-1\t-1\t-1\t-1\t-1\n");
+	else {
+		scsidp = sdp->device;
+		seq_printf(s, "%d\t%d\t%d\t%llu\t%d\t%d\t%d\t%d\t%d\n",
+			      scsidp->host->host_no, scsidp->channel,
+			      scsidp->id, scsidp->lun, (int) scsidp->type,
+			      1,
+			      (int) scsidp->queue_depth,
+			      (int) atomic_read(&scsidp->device_busy),
+			      (int) scsi_device_online(scsidp));
+	}
+	read_unlock_irqrestore(&sg_index_lock, iflags);
+	return 0;
+}
+
+static int sg_proc_open_devstrs(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &devstrs_seq_ops);
+}
+
+static int sg_proc_seq_show_devstrs(struct seq_file *s, void *v)
+{
+	struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
+	Sg_device *sdp;
+	struct scsi_device *scsidp;
+	unsigned long iflags;
+
+	read_lock_irqsave(&sg_index_lock, iflags);
+	sdp = it ? sg_lookup_dev(it->index) : NULL;
+	scsidp = sdp ? sdp->device : NULL;
+	if (sdp && scsidp && (!atomic_read(&sdp->detaching)))
+		seq_printf(s, "%8.8s\t%16.16s\t%4.4s\n",
+			   scsidp->vendor, scsidp->model, scsidp->rev);
+	else
+		seq_puts(s, "<no active device>\n");
+	read_unlock_irqrestore(&sg_index_lock, iflags);
+	return 0;
+}
+
+/* must be called while holding sg_index_lock */
+static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp)
+{
+	int k, m, new_interface, blen, usg;
+	Sg_request *srp;
+	Sg_fd *fp;
+	const sg_io_hdr_t *hp;
+	const char * cp;
+	unsigned int ms;
+
+	k = 0;
+	list_for_each_entry(fp, &sdp->sfds, sfd_siblings) {
+		k++;
+		read_lock(&fp->rq_list_lock); /* irqs already disabled */
+		seq_printf(s, "   FD(%d): timeout=%dms bufflen=%d "
+			   "(res)sgat=%d low_dma=%d\n", k,
+			   jiffies_to_msecs(fp->timeout),
+			   fp->reserve.bufflen,
+			   (int) fp->reserve.k_use_sg,
+			   (int) fp->low_dma);
+		seq_printf(s, "   cmd_q=%d f_packid=%d k_orphan=%d closed=0\n",
+			   (int) fp->cmd_q, (int) fp->force_packid,
+			   (int) fp->keep_orphan);
+		for (m = 0, srp = fp->headrp;
+				srp != NULL;
+				++m, srp = srp->nextrp) {
+			hp = &srp->header;
+			new_interface = (hp->interface_id == '\0') ? 0 : 1;
+			if (srp->res_used) {
+				if (new_interface && 
+				    (SG_FLAG_MMAP_IO & hp->flags))
+					cp = "     mmap>> ";
+				else
+					cp = "     rb>> ";
+			} else {
+				if (SG_INFO_DIRECT_IO_MASK & hp->info)
+					cp = "     dio>> ";
+				else
+					cp = "     ";
+			}
+			seq_puts(s, cp);
+			blen = srp->data.bufflen;
+			usg = srp->data.k_use_sg;
+			seq_puts(s, srp->done ?
+				 ((1 == srp->done) ?  "rcv:" : "fin:")
+				  : "act:");
+			seq_printf(s, " id=%d blen=%d",
+				   srp->header.pack_id, blen);
+			if (srp->done)
+				seq_printf(s, " dur=%d", hp->duration);
+			else {
+				ms = jiffies_to_msecs(jiffies);
+				seq_printf(s, " t_o/elap=%d/%d",
+					(new_interface ? hp->timeout :
+						  jiffies_to_msecs(fp->timeout)),
+					(ms > hp->duration ? ms - hp->duration : 0));
+			}
+			seq_printf(s, "ms sgat=%d op=0x%02x\n", usg,
+				   (int) srp->data.cmd_opcode);
+		}
+		if (0 == m)
+			seq_puts(s, "     No requests active\n");
+		read_unlock(&fp->rq_list_lock);
+	}
+}
+
+static int sg_proc_open_debug(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &debug_seq_ops);
+}
+
+static int sg_proc_seq_show_debug(struct seq_file *s, void *v)
+{
+	struct sg_proc_deviter * it = (struct sg_proc_deviter *) v;
+	Sg_device *sdp;
+	unsigned long iflags;
+
+	if (it && (0 == it->index))
+		seq_printf(s, "max_active_device=%d  def_reserved_size=%d\n",
+			   (int)it->max, sg_big_buff);
+
+	read_lock_irqsave(&sg_index_lock, iflags);
+	sdp = it ? sg_lookup_dev(it->index) : NULL;
+	if (NULL == sdp)
+		goto skip;
+	read_lock(&sdp->sfd_lock);
+	if (!list_empty(&sdp->sfds)) {
+		seq_printf(s, " >>> device=%s ", sdp->disk->disk_name);
+		if (atomic_read(&sdp->detaching))
+			seq_puts(s, "detaching pending close ");
+		else if (sdp->device) {
+			struct scsi_device *scsidp = sdp->device;
+
+			seq_printf(s, "%d:%d:%d:%llu   em=%d",
+				   scsidp->host->host_no,
+				   scsidp->channel, scsidp->id,
+				   scsidp->lun,
+				   scsidp->host->hostt->emulated);
+		}
+		seq_printf(s, " sg_tablesize=%d excl=%d open_cnt=%d\n",
+			   sdp->sg_tablesize, sdp->exclude, sdp->open_cnt);
+		sg_proc_debug_helper(s, sdp);
+	}
+	read_unlock(&sdp->sfd_lock);
+skip:
+	read_unlock_irqrestore(&sg_index_lock, iflags);
+	return 0;
+}
+
+#endif				/* CONFIG_SCSI_PROC_FS */
+
+module_init(init_sg);
+module_exit(exit_sg);